Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/02—Well-drilling compositions
  • C09K8/04—Aqueous well-drilling compositions
  • C09K8/06—Clay-free compositions
  • C09K8/08—Clay-free compositions containing natural organic compounds, e.g. polysaccharides, or derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/40—Spacer compositions, e.g. compositions used to separate well-drilling from cementing masses
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/60—Compositions for stimulating production by acting on the underground formation
  • C09K8/84—Compositions based on water or polar solvents
  • C09K8/86—Compositions based on water or polar solvents containing organic compounds
  • C09K8/88—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
  • C09K8/90—Compositions based on water or polar solvents containing organic compounds macromolecular compounds of natural origin, e.g. polysaccharides, cellulose
  • C09K8/905—Biopolymers

Definitions

• the present invention relates to the use of dicarbonyl compounds for increasing the thermal stability of biopolymers in aqueous liquid phases employed in the field of oil and gas exploration.
• Biopolymers in particular those of fermentative origin, such as, for example, scleroglucan, xanthan gum, succinoglycan, diutan or welan gum, are widely used for viscosity formation in aqueous liquid phases; for example, in cosmetic products or generally in the food industry. Regardless of the various fields of use, the shear-thinning and/or thixotropic thickening of the respective liquid phase is frequently of primary importance.
• biopolymers play a different role in the different drilling applications: in addition to said improvement of the carrying capacity in combination with good pumpability, biopolymer-based shear-thinning fluids also reduce the fluid loss, stabilize soil formations and promote easy separation of the cuttings from the drilling fluid circulation.
• biopolymers are particularly frequently used as thickeners for solids-free drilling fluids, so-called “drill-in fluids”.
• biopolymer-based “drill-in fluids” avoid damage to the reservoir formation, resulting finally in a higher productivity of the oil or gas well.
• biopolymers are frequently an essential constituent of so-called “spacer fluids”, which are used in the run-up to well cementing in order to ensure optimum binding of the cement to the borehole wall.
• aqueous liquid phases are understood in the present context also as meaning those which, in addition to fresh water or sea water, may contain a number of further main or secondary components; this also includes salt-containing systems (so-called “brines”) and more complex drilling fluids, such as, for example, emulsions or invert emulsions, which may also contain large proportions of an oil component.
• salt-containing systems such as, for example, emulsions or invert emulsions, which may also contain large proportions of an oil component.
• biopolymers are suitable for common high-temperature applications in the region of ⁇ 250° F. which are entirely customary in oil and gas exploration.
• Scleroglucan and welan gum may be primarily mentioned here.
• these special polysaccharides have, as a rule, a substantially higher thermal stability which, depending on the conditions of use, is usually 50 to 100° F. above the limit of xanthan gum.
• the comparatively cheap xanthan gum generally declines dramatically in rheological performance even at temperatures substantially below 250° F. (in general from 160° F.). Even before thermal degradation of the xanthan gum molecules occurs, the structural viscosity is “spontaneously” reduced thereby as a result of Brownian molecular movement.
• thermo extenders for hydroxyethylcellulose (HEC) has already been described in WO 02/099258 A1, the use in combination with xanthan gum also being mentioned.
• dicarbonyl compounds are capable of increasing the thermal stability of biopolymers.
• a marked effect is achieved even with the simple binary mixture of, for example, scleroglucan and a dialdehyde.
• a known stabilizer such as, for example, sodium bisulfite.
• This effect of the dicarbonyls is all the more surprising since, owing to their chemical structure and possible reactions, these compounds are not to be assigned to the known category of the reducing agents or “oxygen scavengers” and also do not act as pH buffers in the sense of the abovementioned amines.
• the biopolymer component according to the present invention should preferably be a polysaccharide prepared by fermentation, members of the series consisting of scleroglucan, welan gum, diutan, rhamzan and succinoglycan being regarded as being particularly suitable.
• aqueous liquid phases which constitute a drilling fluid are particularly suitable.
• the observed effect of the increase in the thermal stability is observed to be particularly pronounced in the case of dicarbonyls if this drilling fluid preferably contains fresh water and/or sea water.
• this drilling fluid preferably contains fresh water and/or sea water.
• it should be a salt-containing system of the “brine” type.
• the present invention also includes a variant in which the drilling fluid is an oil-containing emulsion or an invert emulsion.
• dialdehydes such as malonaldehyde CH 2 (CHO) 2 , succinaldehyde C 2 H 4 (CHO) 2 , glutaraldehyde C 3 H 6 (CHO) 2 and preferably the simplest member, glyoxal CHOCHO, have proved to be particularly suitable.
• certain diketones such as, for example, dimethylglyoxal (COCH 3 ) 2 or acetylacetone CH 2 (COCH 3 ) 2 , are also claimed as typical members of the dicarbonyls in the context of this invention.
• dicarboxylic acids and their derivatives namely salts, esters and ethers
• dicarbonyl components are also preferred dicarbonyl components.
• compounds having vicinal carbonyl groups have proved to be particularly suitable.
• ⁇ -dicarbonyl compounds such as, for example, malonic acid, also fulfil the purpose according to the invention.
• the present invention also comprises that the dicarbonyl component is admixed with the liquid phases independently of its chemical composition, although a variant in which the dicarbonyl component is incorporated into the biopolymer in the course of the preparation of said biopolymer is being regarded as being particularly preferred.
• the effect, according to the invention, of the dialdehyde component can be additionally increased by using, in addition to the dicarbonyl component, other compounds which serve for stabilizing the drilling fluid, in particular the biopolymers present therein, and especially for increasing the thermal stability thereof.
• oxygen scavengers such as, for example, lignosulfonates and tannates
• sodium sulfite, sodium bisulfite or formates, i.e. salts of formic acid which are generally known as reducing agents (cf. “Composition and Properties of Drilling and Completion Fluids”, 5th Edition, Darley H. C. H. & Gray G. R., Gulf Publishing Company, Houston, Tex., Pages 480 to 482) are also suitable.
• reducing agents cf. “Composition and Properties of Drilling and Completion Fluids”, 5th Edition, Darley H. C. H. & Gray G. R., Gulf Publishing Company, Houston, Tex., Pages 480 to 482
• radical scavengers such as, for example, sodium sulfite
• Fe 2+ , Ni 2+ or Co 2+ salts can additionally be markedly increased by Fe 2+ , Ni 2+ or Co 2+ salts. These salts presumably act as free radical mediators and thus catalyse the binding of free oxygen radicals.
• the use according to the invention is in principle not bound to any defined temperature range, but the effect of thermal stability is particularly pronounced if the temperatures in the rock formation are >250° Fahrenheit, preferably >75° Fahrenheit and particularly preferably >300° Fahrenheit.
• dicarbonyls are surprisingly excellently suitable for increasing the thermal stability of biopolymers in aqueous liquid phases which are used in oil and gas exploration.
• the success of the use according to the invention is therefore all the more unexpected since compounds having dicarbonyl features cannot be assigned to the classes of compounds known to date which are already known to increase the thermal stability of biopolymers markedly.
• the properties of the respective drilling fluids were determined according to the methods of the American Petroleum Institute (API), guideline RP13B-1.
• API American Petroleum Institute
• the rheologies were measured using an appropriate FANN 35 viscometer at 600, 300, 200, 100, 6 and 3 revolutions per minutes [rpm].
• the measurements at the slow speeds of 6 and 3 rpm are particularly relevant with regard to the structural viscosity and carrying capacity of the fluids.
• the so-called “low shear rheology” was also determined using a Brookfield HAT viscometer at 0.5 rpm. Specifically, the measurements were conducted in each case before and after a thermal treatment (“ageing”) over 16 hours in a roller oven customary in the industry, at the temperatures stated in each case.
• the increase in the temperature stability of a salt-containing aqueous solution of scleroglucan by glyoxal is described.
• the scleroglucan component used was the BIOVIS® product from Degussa Construction Polymers GmbH (comparison); in the experiments according to the invention, the BIOVIS® product contained an amount of ⁇ 1% of glyoxal (“+G”) in addition to scleroglucan.
• the increase in the thermal stability of a calcium chloride-loaded, aqueous solution of scleroglucan by glyoxal is described.
• the scleroglucan component used was the BIOVIS® product from Degussa Construction Polymers GmbH (comparison); in the experiments according to the invention, the BIOVIS® product contained an amount of ⁇ 1% of glyoxal (“+G”) in addition to scleroglucan.
• a CaCl 2 -containing aqueous solution 155 g of CaCl 2 and 307 g of water
• HBM Hamilton Beach Mixer
• 3.5 g of the respective BIOVIS® component 1 g of sodium sulfite (stabilizer), 0.25 g of Fe II SO 4 as a free radical mediator and 1 ml of tributyl phosphate (antifoam) were added.
• BHR before hot roll
• glyoxal Increasing the thermal stability of an aqueous solution of welan gum by addition of glyoxal is described.
• the welan gum component used was the product BIOZAN® from CP Kelco.
• Glyoxal was used in the form of a commercially available 40% aqueous solution.
• the fluid was contaminated by addition of a freshly prepared cement slurry in order to simulate the conditions of use as “spacer fluid”.
• HBM Hamilton Beach Mixer
• BIOZAN® 1.0 g of Na 2 SO 3 (stabilizer) and 1 ml of tributyl phosphate (antifoam) were added.
• 0.35 ml of glyoxal solution was added to one of the two batches of this type which were prepared simultaneously (invention).
• 50 g of a cement slurry consististing of 800 g of class H cement from Lafarge and 304 g of water, stirred beforehand for 20 min in an atmospheric consistometer at 60° C.

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• 2006
  • 2006-06-26 DE DE102006029265A patent/DE102006029265A1/de not_active Withdrawn
  • 2006-10-30 US US11/590,659 patent/US20070287638A1/en not_active Abandoned
• 2007
  • 2007-06-25 EP EP07764842A patent/EP2035525A1/fr not_active Withdrawn
  • 2007-06-25 WO PCT/EP2007/005614 patent/WO2008000427A1/fr active Application Filing
  • 2007-06-25 CA CA002655837A patent/CA2655837A1/fr not_active Abandoned
  • 2007-06-25 MX MX2009000251A patent/MX2009000251A/es unknown
• 2009
  • 2009-01-06 NO NO20090076A patent/NO20090076L/no not_active Application Discontinuation

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